Repair of mandibular and maxillary fractures and osteotomies requires bringing the bone fragments into the proper position and alignment followed by temporary fixation of the upper and lower teeth in proper occlusion. Head and neck tumor reconstruction surgery also requires intermaxillary fixation to ensure proper alignment of the reconstructed jaws. Orthognathic surgery similarly requires maxillomandibular fixation that is typically achieved by using hooks the orthodontist attaches to arch wires. However, in orthognathic surgery, it is not uncommon for these brackets to loosen from the teeth and render them useless for intermaxillary fixation. Arch bars are often used in all the above circumstances to achieve intermaxillary fixation, but the arch bars are difficult to secure to the teeth, especially if the patients have pre-existing orthodontic appliances.
Arch bars are conventionally secured to the teeth by wires looped around the teeth or by direct bonding to the teeth, as disclosed in U.S. Pat. Nos. 3,474,779; 4,904,188; and 6,086,365. The front surfaces of the upper and lower arch bars typically have lugs or hooks, around which ligatures are applied to interconnect the upper and lower arch bars and provide fixation of the maxilla (upper jaw bone) and mandible (lower jaw bone). The dental arch bars disclosed in the prior art, however, are time-consuming to secure to the teeth and can cause puncture injuries to clinicians during installation, increasing the risk of disease transmission. Another disadvantage of such arch bars is that they may, depending on how many teeth are missing, not provide satisfactory fixation in an edentulous or partially edentulous patient. Moreover, circumdental wire fixation of arch bars to teeth requires anesthesia, is time consuming, and can cause periodontal injury to the patient.
An alternative to the dental arch bar is the direct placement of screws into the maxilla and mandible with ligatures used to interconnect the screws. For example, Synthes® offers an IMF Screw Set for temporary, perioperative stabilization of occlusion. A minimum of four screws are used, one on each side of the maxilla and one on each side of the mandible. The screws are placed superior to the maxillary tooth roots and inferior to the mandibular tooth roots, with care to also avoid the nerves within the maxilla and mandible. KLS Martin L. P. sells a similar fixation system in which 3-4 screws are placed in each of the maxilla and mandible and then interconnected with wire ligatures. These systems are contraindicated in patients with comminuted or displaced fractures. Further, these systems apply tension across discrete points rather than more evenly distributing tension across an extent of the maxilla and mandible. If the wires that traverse the jaws to provide maxillomandibular fixation stretch, the teeth can slide over one another and compromise the intermaxillary fixation. Additionally, because only several wires connect the maxillary screws to the mandibular screws, there is an uneven application of force providing the maxillomandibular fixation. In areas directly under the wire, premature contacts of the teeth may develop. In the areas between the intermaxillary wires, less pressure may result in regions where the teeth do not touch, producing an area of open bite.
Tellio{hacek over (g)}lu et al. (Eur. J. Plast. Surg., 1998, 21:215-216) disclose a method in which screws are placed directly into the maxilla, and an arch bar is placed over the screws and fastened with wires. A conventional arch bar is placed on the lower teeth without being attached by screws in the mandible. The arch bars are then interconnected with elastic ligatures. Gibbons et al. (British Journal of Oral and Maxillofacial Surgery, 2005, 43:365) disclose treatment of a fracture in a patient with two fixed bridges in the upper jaw using a dental arch bar secured by wires threaded through self-tapping screws placed in the alveolar bone of the maxilla. Because both of these described techniques use wires to secure the arch bar to the screws, mobility will occur as the wires undergo their normal tendency to stretch. The additional wiring takes time and exposes the clinician to the same puncture risk as conventional arch bars.